The United Nations said on Friday at least 26 people were killed in the rocket attack targeting Camp Liberty near the Baghdad's International Airport. The camp houses the exiled Iranian opposition group - Mujahideen Khalq.
"The Secretary-General condemns the attack yesterday on Camp Hurriya, near the Baghdad International Airport, which left at least 26 residents dead and many more wounded," Ban Ki moon's spokesman said in a statement.
According to the Iraqi police over 15 rockets hit the former US military base Camp Liberty on Thursday.
"Fifteen rockets were fired from Bakriya around and on the edge of Camp Liberty," an operation Command in Baghdad said.
The camp was a former United States military base, but after the US withdrawal in 2011, the Iranian opposition People's Mujahedin of Iran moved to the camp. The group had been in exiled from Iran since the 1979 Islamic revolution.
People's Mujahedin of Iran, also known as MEK, supported the former Iraqi President Saddam Hussein during the War with Iran in the 1980.
The group's existence in Iraq is considered illegal by the current Iraqi government - who has connections to Tehran.
The group had accused the Iraqi government of abusing human rights, as they claim worsening health conditions in their isolated camp.
However, security sources said that they had found the truck where the rockets were launched from.
The rocket attack killed at least three Iraqi soldiers, the Iraqi Interior Ministry said.
"We were in our housing trailers when missiles started to fall...Not everybody managed to take shelter," a spokesman for the Mujahedin said.
No group has claimed responsibility for the attack.